The control system of a brushless motor generally includes a controller that generates control signals for exciting phase windings of the motor. The control signals are typically generated at times relative to edges of a rotor signal. The controller may adjust the timing of the control signals in response to, for example, changes in motor speed or excitation voltage so as to achieve a particular performance. The timing of the control signals may be adjusted for each edge of the rotor signal. As a result, the controller responds relatively quickly to any changes in motor speed or excitation voltage. However, for a high-speed motor, adjusting the timing of the control signals this frequently requires a relatively fast and thus expensive controller. Alternatively, the timing of the control signals may be adjusted after a fixed number of edges of the rotor signal. However, since the interval between edges of the rotor signal depends on the speed of the motor, the controller would then adjust the timing of the control signals less frequently at lower speeds and more frequently at higher speeds. This may then adversely affect the performance of the motor.